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Rockhopper M^3 - The Review
Apr 12, 2009 at 12:54 PM Post #332 of 523
Quote:

Originally Posted by Nidhogg22 /img/forum/go_quote.gif
Has anyone compared this to the Audio GD Compass?



No, but I think someone is bringing a Compass to the Atlanta Meet on the 25th so I will be doing some comparisons.
 
Apr 12, 2009 at 9:43 PM Post #333 of 523
Quote:

Originally Posted by deaconblues /img/forum/go_quote.gif
I'm really enjoying the AD843. It's punchier than the OPA627 but not quite as far forward as the AD8610.


That was my impression too, deacon, but there was a volume difference between the chips, with the 843s appearing louder, that made it hard for me to tell which chip was brighter, or forward, as you put it. No doubt the 843s had a punchier bass.

USG
 
Apr 12, 2009 at 9:51 PM Post #334 of 523
Quote:

Originally Posted by analogbox /img/forum/go_quote.gif
I haven't critically compared the two (627/637 vs. 8610s) but the difference was quite obvious without any extensive comparison.

8610s in both ground and L/R channel resulted in very bright, lively sound. Treble was more extended than the other set up but I felt a hair less presence in the mid.

627 in the ground and 8610s in the L/R channel sounded very similar to the all 8610 set up and I may have to do more comparison to be able to tell the difference.

The original set up which was 627/637 set up had a very all around sound, IMO. It's very warm from top to bottom and has a Sennheiser sound. My main gripe with this set up was it's somewhat laid back high. Compared to my amp One and Move, the highs didn't have the sparkling clarity which 8610s did.

For now, I've put back the 627/637s back because I'm listening to lots of vocal stuff, but I plan to switch to 8610s set up when I get my new classical CDs. I think that's where the 8610s really excel.


Hi analog

OK, we pretty much agree on how the two chips sound.
biggrin.gif


Now, if it's alright with you, I'd like to continue this back channel because an in depth chip discussion is off topic for this thread.

USG

Edit: Cipher, you might be interested in this too so I will e-mail you as well.
 
Apr 13, 2009 at 12:43 AM Post #335 of 523
Apr 13, 2009 at 4:50 AM Post #336 of 523
Why not discuss the sound of the opamps here for everyone to learn from?
Isn't this what the forum is for?
 
Apr 13, 2009 at 4:58 AM Post #337 of 523
Quote:

Originally Posted by stellablues /img/forum/go_quote.gif
Why not discuss the sound of the opamps here for everyone to learn from?
Isn't this what the forum is for?


We should make another thread for discussing M^3 opamp choices then....

USG
 
Apr 13, 2009 at 4:58 AM Post #338 of 523
Quote:

Originally Posted by Nidhogg22 /img/forum/go_quote.gif
Has anyone compared this to the Audio GD Compass?


I have both the Rock M^3 and the Compass in my house right now. The m^3 came about two weeks ago and the Compass last wednesday. It is too early to tell how close the Compass gets to the Rock but neither is really broken-in yet. Also the Compass has OPAs which you can roll. I am listening to the Moon right now which has about 40 hours and my Earth is still fresh from the packaging.
 
Apr 13, 2009 at 5:02 AM Post #339 of 523
Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif
We should make another thread for discussing M^3 opamp choices then....

USG


Thanks, I would hate to loose a valuable discussion ... I really like how the 8610s are breaking in but now I have the Compass and its OPAs to mess with. I think Rock will stay the reference amp though (once i can score a sigma), so I want to keep abreast of your guys findings.
 
Apr 13, 2009 at 5:14 AM Post #341 of 523
I've got the AD843JNZ. My "not as far forward comment" was pretty much directed at the more restrained treble compared to the 8610. I find the 8610 to be enjoyable with my HD650 but unlistenable with the K701, while I love the AD843 on both headphones. As for the OPA627s, they're now just sitting in a tube in my drawer. I'm thinking about building a PPA, and I'll probably put the OPA627s in there.

One thing I'm wondering about is whether the ground channel opamp really matters. Since it doesn't actually amplify any audio signal, I'm thinking that the opamp's characteristics may not affect the sound as much as the L/R channel opamps do. I wonder if it would be fine to simply put a cheap reliable opamp in there and forget about it. I'd like to test it for differences, but I have the feeling that I would have to build another M3 so I could switch instantly between configurations rather than relying on my memory after going through the process of waiting for the caps to discharge then replacing the opamp.
 
Apr 13, 2009 at 6:20 AM Post #342 of 523
Apr 13, 2009 at 6:55 AM Post #343 of 523
Quote:

Originally Posted by deaconblues /img/forum/go_quote.gif
One thing I'm wondering about is whether the ground channel opamp really matters. Since it doesn't actually amplify any audio signal, I'm thinking that the opamp's characteristics may not affect the sound as much as the L/R channel opamps do. I wonder if it would be fine to simply put a cheap reliable opamp in there and forget about it.


It does matter.

It's true that the ground channel opamp doesn't swing any voltage, but in the M³ the ground channel MOSFET output stage sources and sinks the return current from the headphones, and how well it does the job is tightly related to the opamp that drives them. In particular, the opamp is where the overall negative feedback loop is applied and it is a crucial part of the overall performance. This is no different in the ground channel as they are in the left and right channels.

The ground channel opamp should be every bit as good as the left and right opamps. I don't know what's meant by "cheap reliable opamp", but if it's something like a TL081 then the ground channel will become a serious performance bottleneck.
 
Apr 13, 2009 at 7:32 AM Post #344 of 523
Quote:

Originally Posted by stellablues /img/forum/go_quote.gif
I have both the Rock M^3 and the Compass in my house right now. The m^3 came about two weeks ago and the Compass last wednesday. It is too early to tell how close the Compass gets to the Rock but neither is really broken-in yet. Also the Compass has OPAs which you can roll. I am listening to the Moon right now which has about 40 hours and my Earth is still fresh from the packaging.


Cool, keep us updated please!
 
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